A multiplicity of assembling-disassembling techniques have been suggested and extensive studies and searches have been carried out over time to find a solution to this problem.
Thus, for example, patent IT-1 319 475 describes a tire assembling-disassembling machine provided with rotatable means for supporting a wheel rim, and an automatic device for assembling-disassembling a tire. Such an automatic device has a arm extending cantileverwise, which can move both radially and axially with respect to a wheel rim arranged on the rotatable supporting means, that supports a hook-type assembling tool at its free end, the assembling tool being articulated at its head thereby extending transversally with respect to the arm. The assembling tool can be controlled to effect angular movements about its axis of rotation by a linkage system controlled by a double-acting jack. At the beginning, the tool is located in a lifted position and is lowered by the supporting arm until its hook end contacts the area between tire and wheel rim, and the tire bead is pressed downwards. At the same time, the tool is rotated about its articulation pin through an angle α in the direction in which its free hook-type end moves closer to the wheel rim. Such a rotation assist the tire bead in being hooked by the hook-type end of the tool. At this point, the tool-carrying arm is caused to move upwards, and thus the tool moves with it the tire bead until it is extended beyond the wheel rim edge. The wheel rim is then set in rotation so that the tire bead is progressively carried outside the wheel rim edge, while sliding along the hook portion of the tool. If desired, in this latter step, the tool can be rotated through an angle β in the direction in which the hook edge moves away from the wheel rim thereby assisting in the bead extraction. In all disassembling steps has its hook back of the tool is facing the wheel rim, whereas the hook portion proper is facing the tire. The tool, however, is not free, but it is driven and held firmly in position during all the steps needed for disassembling the tire from its control linkage.
Obviously, such a technical solution, on the one hand, is very expensive to be carried out and, on the other, requires a skilled operator in order to avoid damaging the wheel rim and/or the tire during the assembling-disassembling steps.
Patent Application No. US-2004/0 055 712 discloses a particular embodiment of an assembling-disassembling tool fully similar to that described in IT-1 319 475.
Patent EP-1 459 913 discloses a tire assembling-disassembling machine provided with a rotatable wheel-carrying table, which can be moved near to, or away from, a rear support upright, and a tire assembling-disassembling device. The assembling-disassembling device is supported by a sleeve slidable along a guide member parallel to the support upright. An ear of a tool-carrying bush is articulated to the sleeve, the tool being formed by a rod iron with a hook-shaped end which is mounted for rotation in the bush and can be controlled by a double-acting jack so that it can effect angular movements about the axis of the bush. The tool is first moved against to the area between bead and wheel rim edge, with its hook-shaped end being tangentially directed with respect to the wheel rim, it is then driven beyond the tire edge, the tool is caused to rotate through about 90° to allow the hook-shaped end thereof to climb over and engage with the edge of the tire bead, and finally a tire edge portion is extracted and the wheel is subsequently caused to rotate.
Also this assembling-disassembling tool then requires an operation by means of mechanisms controlled by an operator and this, on one hand, results in considerable costs for the tool adjusting and control system, and on the other mistakes are likely to occur owing to a wrong evaluation of the trim (especially the inclination) of the tool with respect to the wheel rim or the tire, which might result in the tool stumbling in the tire edge thereby damaging it.